As well known in the related art, a heat exchanger is a device for transferring heat from a higher temperature fluid to a lower temperature fluid through a heat transfer wall, and a heat exchanger for automobiles is typically used in an air conditioning system, a transmission oil cooler, etc. Particularly, to accommodate the heat exchanger for automobiles in the limited space provided for its installation, it is required to realize compactness of the heat exchanger and, accordingly, a plate heat exchanger has been widely used.
The plate heat exchanger includes a plurality of heat exchange plates that are stacked to face each other and to define a flow channel between neighboring plates. The flow channel includes at least two flow channels through which different fluids flow. In the plate heat exchanger, the different fluids exchange heat with each other through the heat exchange plates when the fluids pass through the respective flow channels. Further, each of the respective plates has an inlet port and an outlet port in opposite ends thereof.
Further, to realize desired heat exchange performance of the plate heat exchanger, it is required to let the respective fluids smoothly flow without stagnating at specific locations and maintain a steady turbulence.